In recent years, in an electronic apparatus such as a digital camera or a mobile information terminal, external memory including semiconductor memory such as a memory card or flash memory, inserted/removed for use has been widely used to record and retain data. To prevent data destruction and malfunction from occurring at the inserting or removing, the electronic apparatus using such external memory is provided with an insertion/removal detector for detecting insertion and removal of external memory into and from a connector.
Hitherto, as this kind of insertion/removal detector, for example, a device has been available for detecting insertion and removal of external memory by connecting a resistor in series to a power line for supplying power to a memory card as external memory of a terminal and determining whether the voltage across the ends is high or low (for example, refer to patent document 1).
However, it is difficult to apply the conventional insertion/removal detector described above to a terminal requiring a power saving function or a terminal which must be operated with limited power because power needs to be always supplied to the memory card, and there is a demand for an insertion/removal detector for enabling power to be supplied only at the necessary time.
There is a device including an insertion detection switch for detecting insertion of a memory card into a terminal and a pull-down contact for determining the type of inserted memory card, the device for detecting insertion of only a memory card that can be applied to the terminal as the insertion detection switch is turned on and the pull-down contact goes high (for example, refer to patent document 2).
In this example, since insertion and removal of a memory card are detected mechanically by the insertion detection switch, it is unnecessary to always supply power. However, to insert a memory card through an adapter, if only the memory card is removed or inserted with the adapter left in a slot of the terminal, the insertion detection switch is always held on because the adapter remains inserted. Thus, removal or insertion of only the memory card cannot be detected.
In a terminal for storing data of a memory card in internal memory of the terminal or a terminal for referencing data recorded in internal memory to access a memory card, when the memory card is replaced, removal or insertion of only the memory card cannot be detected. Thus, there is a possibility that erroneous data may be recorded or that the data in a new memory card may be destroyed by accessing the new memory card in a similar way to access the replaced old memory card.
Patent document 1: JP-A-6-131079
Patent document 2: JP-A-11-85915